U.S. Pat. No. 6,880,507 discloses valve lift devices, in particular, roller lifters, for example, the previously known lifter at FIG. 2. U.S. Pat. No. 7,363,894 also discloses roller lifters.
Valvetrain components, such as roller lifters, in medium to heavy-duty engines have generally used a roller axle, often comprising a bronze pin supporting plain bearings. This is necessary to carry the heavy loads in a size efficient package. For such designs, lubrication of the roller axle to plain bearing contact area is necessary to reduce friction and wear.